The Impact Of Star-Formation-Rate Surface Density On The Electron Density And Ionization Parameter Of High-Redshift Galaxies,
2023
University of California - Riverside
The Impact Of Star-Formation-Rate Surface Density On The Electron Density And Ionization Parameter Of High-Redshift Galaxies, Naveen Reddy, Ryan L. Sanders, Alice E. Shapley, Michael W. Topping, Mariska Kriek, Alison L. Coil, Bahram Mobasher, Brian Siana, Saeed Rezaee
Physics and Astronomy Faculty Publications
We use the large spectroscopic data set of the MOSFIRE Deep Evolution Field survey to investigate some of the key factors responsible for the elevated ionization parameters (U) inferred for high-redshift galaxies, focusing in particular on the role of star-formation-rate surface density (ΣSFR). Using a sample of 317 galaxies with spectroscopic redshifts z spec ≃ 1.9-3.7, we construct composite rest-frame optical spectra in bins of ΣSFR and infer electron densities, n e, using the ratio of the [O ii] λ λ3727, 3730 doublet. Our analysis suggests a significant (≃3σ) correlation between n e and ΣSFR …
Beam Energy Dependence Of The Linear And Mode-Coupled Flow Harmonics In Au+Au Collisions,
2023
University of Kentucky
Beam Energy Dependence Of The Linear And Mode-Coupled Flow Harmonics In Au+Au Collisions, Star Collaboration
Physics and Astronomy Faculty Publications
The linear and mode-coupled contributions to higher-order anisotropic flow are presented for Au+Au collisions at √sNN = 27, 39, 54.4, and 200 GeV and compared to similar measurements for Pb+Pb collisions at the Large Hadron Collider (LHC). The coefficients and the flow harmonics’ correlations, which characterize the linear and mode-coupled response to the lower-order anisotropies, indicate a beam energy dependence consistent with an influence from the specific shear viscosity (η /s). In contrast, the dimensionless coefficients, mode-coupled response coefficients, and normalized symmetric cumulants are approximately beam-energy independent, consistent with a significant role from initial- state effects. These measurements could provide …
Energy Dependence Of Intermittency For Charged Hadrons In Au+Au Collisions At Rhic,
2023
University of Kentucky
Energy Dependence Of Intermittency For Charged Hadrons In Au+Au Collisions At Rhic, The Star Collaboration
Physics and Astronomy Faculty Publications
Density fluctuations near the QCD critical point can be probed via an intermittency analysis in relativistic heavy-ion collisions. We report the first measurement of intermittency in Au+Au collisions at √sNN = 7.7-200 GeV measured by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The scaled factorial moments of identified charged hadrons are analyzed at mid-rapidity and within the transverse momentum phase space. We observe a power-law behavior of scaled factorial moments in Au+Au collisions and a decrease in the extracted scaling exponent (ν) from peripheral to central collisions. The ν is consistent with a constant for different collisions …
Global Polarization Of Λ And Λ¯ Hyperons In Au+Au Collisions At √S Nn = 19.6 And 27 Gev,
2023
University of Kentucky
Global Polarization Of Λ And Λ¯ Hyperons In Au+Au Collisions At √S Nn = 19.6 And 27 Gev, Star Collaboration
Physics and Astronomy Faculty Publications
In relativistic heavy-ion collisions, a global spin polarization, PH, of Λ and Λ¯ hyperons along the direction of the system angular momentum was discovered and measured across a broad range of collision energies and demonstrated a trend of increasing PH with decreasing √sNN. A splitting between Λ and Λ¯ polarization may be possible due to their different magnetic moments in a late-stage magnetic field sustained by the quark-gluon plasma which is formed in the collision. The results presented in this study find no significant splitting at the collision energies of √sNN=19.6 and 27 GeV in the BNL Relativistic Heavy Ion …
Measurements Of Dielectron Production In Au + Au Collisions At √Snn = 27, 39, And 62.4 Gev From The Star Experiment,
2023
University of Kentucky
Measurements Of Dielectron Production In Au + Au Collisions At √Snn = 27, 39, And 62.4 Gev From The Star Experiment, Star Collaboration
Physics and Astronomy Faculty Publications
We report systematic measurements of dielectron (e+e−) invariant-mass Mee spectra at midrapidity in Au + Au collisions at √s NN = 27, 39, and 62.4 GeV taken with the STAR detector at the Relativistic Heavy Ion Collider. For all energies studied, a significant excess yield of dielectrons is observed in the low-mass region (0.40 < M ee < 0.75 MeV/c2 ) compared to hadronic cocktail simulations at freeze-out. Models that include an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess. In addition, we report acceptance-corrected dielectron-excess spectra for Au + Au collisions at midrapidity (|yee| < 1) in the 0–80% centrality bin for each collision energy. The integrated excess yields for 0.4 < Mee < 0.75 GeV/c2 , normalized by the charged particle multiplicity at midrapidity, are compared with previously published measurements for Au + Au at √s NN = 19.6 and 200 GeV. Models that include an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess. The normalized excess yields in the low-mass region show no significant collision energy dependence. The data, however, are consistent with model calculations that demonstrate a modest energy dependence.
Measurements Of The Elliptic And Triangular Azimuthal Anisotropies In Central 3he + Au, D + Au And P + Au Collisions At √Snn P = 200 Gev,
2023
University of Kentucky
Measurements Of The Elliptic And Triangular Azimuthal Anisotropies In Central 3he + Au, D + Au And P + Au Collisions At √Snn P = 200 Gev, Star Collaboration
Physics and Astronomy Faculty Publications
The elliptic (v2) and triangular (v3) azimuthal anisotropy coefficients in central He3+Au, d+Au, and p+Au collisions at sNN=200 GeV are measured as a function of transverse momentum (pT) at midrapidity (|η|< 0.9), via the azimuthal angular correlation between two particles both at |η|< 0.9. While the v2(pT) values depend on the colliding systems, the v3(pT) values are system independent within the uncertainties, suggesting an influence on eccentricity from subnucleonic fluctuations in these small-sized systems. These results also provide stringent constraints for the hydrodynamic modeling of these systems.
K∗0 Production In Au + Au Collisions At √Snn = 7.7, 11.5, 14.5, 19.6, 27, And 39 Gev From The Rhic Beam Energy Scan,
2023
University of Kentucky
K∗0 Production In Au + Au Collisions At √Snn = 7.7, 11.5, 14.5, 19.6, 27, And 39 Gev From The Rhic Beam Energy Scan, Star Collaboration
Physics and Astronomy Faculty Publications
We report the measurement of K∗0 meson at midrapidity (|y| < 1.0) in Au + Au collisions at √sNN = 7.7, 11.5, 14.5, 19.6, 27, and 39 GeV collected by the STAR experiment during the Relativistic Heavy Ion Collider (RHIC) beam energy scan program. The transverse momentum spectra, yield, and average transverse momentum of K∗0 are presented as functions of collision centrality and beam energy. The K∗0/K yield ratios are presented for different collision centrality intervals and beam energies. The K∗0/K ratio in heavy-ion collisions are observed to be smaller than that in small-system collisions (e + e and p + p). The K∗0/K ratio follows a similar centrality dependence to that observed in previous RHIC and Large Hadron Collider measurements. The data favor the scenario of the dominance of hadronic rescattering over regeneration for K∗0 production in the hadronic phase of the medium.
Observation Of Directed Flow Of Hypernuclei 3/Λ H And 4/Λ H In √𝑠nn=3 Gev Au+Au Collisions At Rhic,
2023
University of Kentucky
Observation Of Directed Flow Of Hypernuclei 3/Λ H And 4/Λ H In √𝑠nn=3 Gev Au+Au Collisions At Rhic, Star Collaboration
Physics and Astronomy Faculty Publications
We report here the first observation of directed flow (v1) of the hypernuclei H/Λ 3 and H/Λ 4 in mid-central Au+Au collisions at √sNN=3 GeV at RHIC. These data are taken as part of the beam energy scan program carried out by the STAR experiment. From 165×106 events in 5%-40% centrality, about 8400 H/Λ 3 and 5200 H/Λ 4 candidates are reconstructed through two- and three-body decay channels. We observe that these hypernuclei exhibit significant directed flow. Comparing to that of light nuclei, it is found that the midrapidity v1 slopes of H/Λ 3 and H/Λ 4 follow baryon number …
Pion, Kaon, And (Anti)Proton Production In U+U Collisions At √Snn = 193 Gev Measured With The Star Detector,
2023
University of Kentucky
Pion, Kaon, And (Anti)Proton Production In U+U Collisions At √Snn = 193 Gev Measured With The Star Detector, Star Collaboration
Physics and Astronomy Faculty Publications
We present the first measurements of transverse momentum spectra of π±, K±, p( ¯p) at midrapidity (|y| < 0.1) in U+U collisions at √s NN = 193 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The centrality dependence of particle yields, average transverse momenta, particle ratios and kinetic freeze-out parameters are discussed. The results are compared with the published results from Au+Au collisions at √s NN = 200 GeV in STAR. The results are also compared to those from A Multi-Phase Transport ( AMPT) model.
Search For The Chiral Magnetic Effect In Au+Au Collisions At √Snn = 27 Gev With The Star Forward Event Plane Detectors,
2023
University of Kentucky
Search For The Chiral Magnetic Effect In Au+Au Collisions At √Snn = 27 Gev With The Star Forward Event Plane Detectors, Star Collaboration
Physics and Astronomy Faculty Publications
A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at √sNN = 27 GeV. We measure elliptic flow scaled charge-dependent correlators relative …
Search For The Chiral Magnetic Wave Using Anisotropic Flow Of Identified Particles At Energies Available At The Bnl Relativistic Heavy Ion Collider,
2023
University of Kentucky
Search For The Chiral Magnetic Wave Using Anisotropic Flow Of Identified Particles At Energies Available At The Bnl Relativistic Heavy Ion Collider, Star Collaboration
Physics and Astronomy Faculty Publications
The chiral magnetic wave (CMW) has been theorized to propagate in the deconfined nuclear medium formed in high-energy heavy-ion collisions and to cause a difference in elliptic flow (𝑣2) between negatively and positively charged hadrons. Experimental data consistent with the CMW have been reported by the STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC), based on the charge asymmetry dependence of the pion 𝑣2 from Au +Au collisions at √𝑠𝑁𝑁=27 to 200 GeV. In this comprehensive study, we present the STAR measurements of elliptic flow and triangular flow of charged pions, along with the 𝑣2 of charged kaons and …
Ecce Sensitivity Studies For Single Hadron Transverse Single Spin Asymmetry Measurements,
2023
RIKEN Nishina Center
Ecce Sensitivity Studies For Single Hadron Transverse Single Spin Asymmetry Measurements, R. Seidl, A. Vladimirov, D. Pitonyak, A. Prokudin
Physics and Astronomy Faculty Publications
We performed feasibility studies for various single transverse spin measurements that are related to the Sivers effect, transversity and the tensor charge, and the Collins fragmentation function. The processes studied include semi-inclusive deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The data were obtained in pythia6 and geant4 simulated e+p collisions at 18 GeV on 275 GeV, 18 on 100, 10 on 100, and 5 on 41 that use the ECCE detector configuration. Typical DIS kinematics were selected, most notably 𝑄2 > 1 GeV2, and cover the 𝑥 range from …
Exclusive J/𝜓 Detection And Physics With Ecce,
2023
Morehead State University
Exclusive J/𝜓 Detection And Physics With Ecce, X. Li
Physics and Astronomy Faculty Publications
The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been recommended as a reference design for the proposed Electron-Ion Collider (EIC) program. This paper presents simulation studies of exclusive J/𝜓 detection and selected physics impact results in EIC using the projected ECCE detector concept. Exclusive quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. Preliminary results estimate the excellent statistics benefited from the large cross section of …
Beam Energy Dependence Of Fifth- And Sixth-Order Net-Proton Number Fluctuations In Au + Au Collisions At Rhic,
2023
University of Kentucky
Beam Energy Dependence Of Fifth- And Sixth-Order Net-Proton Number Fluctuations In Au + Au Collisions At Rhic, Star Collaboration
Physics and Astronomy Faculty Publications
We report the beam energy and collision centrality dependence of fifth and sixth order cumulants (C5, C6) and factorial cumulants (κ5, κ6) of net-proton and proton number distributions, from center-of-mass energy (sNN) 3 GeV to 200 GeV Au+Au collisions at RHIC. Cumulant ratios of net-proton (taken as proxy for net-baryon) distributions generally follow the hierarchy expected from QCD thermodynamics, except for the case of collisions at 3 GeV. The measured values of C6/C2 for 0%-40% centrality collisions show progressively negative trend with decreasing energy, while it is positive for the lowest energy studied. These observed negative signs are consistent with …
Bifurcation Levels Of The Integral Manifolds Of The Newtonian N-Body Problem,
2023
Northern Illinois University
Bifurcation Levels Of The Integral Manifolds Of The Newtonian N-Body Problem, Hannah G. Havel
CURE Proceedings
The N-body problem, first proposed by Isaac Newton, is a field of study in mathematics and physics that involves predicting the motion of particles moving under their mutual gravitational attraction. It has significance to many areas of science, including physics and computer science, and is crucial in understanding how the universe works. In fact, it was a primary motivation for Newton's development of calculus. An important application of the N-body problem is within celestial mechanics and involves how planets and other celestial bodies move with mutual gravitational attraction. It is important in developing how satellites behave in space using complicated …
Accurate Oxygen Abundance Of Interstellar Gas In Mrk 71 From Optical And Infrared Spectra,
2023
University of California, Davis
Accurate Oxygen Abundance Of Interstellar Gas In Mrk 71 From Optical And Infrared Spectra, Yuguang Chen, Tucker Jones, Ryan Sanders, Dario Fadda, Jessica Sutter, Robert Minchin, Erin Huntzinger, Peter Senchyna, Daniel Stark, Justin Spilker, Benjamin J. Weiner, Guido Roberts-Borsani
Physics and Astronomy Faculty Publications
The heavy element content (“metallicity”) of the Universe is a record of the total star formation history. Gas-phase metallicity in galaxies, as well as its evolution with time, is of particular interest as a tracer of accretion and outflow processes. However, metallicities from the widely-used electron temperature (Te) method are typically ∼ 2× lower than the values based on the recombination line method. This “abundance discrepancy factor” (ADF) is well known and is commonly ascribed to bias due to temperature fluctuations. We present a measurement of oxygen abundance in the nearby (3.4 Mpc) system, Mrk 71, using a combination of …
Excitation And Ionization Properties Of Star-Forming Galaxies At Z = 2.0-9.3 With Jwst/Nirspec,
2023
University of Kentucky
Excitation And Ionization Properties Of Star-Forming Galaxies At Z = 2.0-9.3 With Jwst/Nirspec, Ryan L. Sanders, Alice E. Shapley, Michael W. Topping, Naveen Reddy, Gabriel B. Brammer
Physics and Astronomy Faculty Publications
We utilize medium-resolution JWST/NIRSpec observations of 164 galaxies at z = 2.0-9.3 from the Cosmic Evolution Early Release Science (CEERS) survey to investigate the evolution of the excitation and ionization properties of galaxies at high redshifts. Our results represent the first statistical constraints on the evolution of the [O III]/Hβ versus [N II]/Hα, [S II]/Hα, and [O I]/Hα “BPT” diagrams at z > 2.7, and the first analysis of the O32 versus R23 diagram at z > 4 with a large sample. We divide the sample into five redshift bins containing 30-40 galaxies each. The subsamples at z ∼ 2.3, …
Clusters, Curves, And Centroids: Stellar Flare Morphology In The Ultraviolet,
2023
Claremont Colleges
Clusters, Curves, And Centroids: Stellar Flare Morphology In The Ultraviolet, Vera Berger
Pomona Senior Theses
With a novel sample of 495 high-cadence light curves for stellar flares in the near-ultraviolet, I explore similarity measures, clustering algorithms, averaging methods, and curve fitting techniques for time series. This work seeks to provide insight into whether stellar flares are similar across stars, if we can identify physically meaningful patterns in their light curves, and how to construct a comprehensive model for flares. I construct the first empirical template for flare light curves in the ultraviolet, and compute ``average elements" of flares displaying complex features such as quasi-periodic oscillations and multipeak structures. Developing accurate models for flares in the …
Infrared Spectra Of Small Radicals For Exoplanetary Spectroscopy: Oh, Nh, Cn, And Ch: The State Of Current Knowledge,
2023
Old Dominion University
Infrared Spectra Of Small Radicals For Exoplanetary Spectroscopy: Oh, Nh, Cn, And Ch: The State Of Current Knowledge, Svatopluk Civiš, Adam Pastorek, Martin Ferus, Sergei N. Yurchenko, Noor-Ines Boudjema
Chemistry & Biochemistry Faculty Publications
In this study, we present a current state-of-the-art review of middle-to-near IR emission spectra of four simple astrophysically relevant molecular radicals—OH, NH, CN and CH. The spectra of these radicals were measured by means of time-resolved Fourier transform infrared spectroscopy in the 700–7500 cm−1 spectral range and with 0.07–0.02 cm−1 spectral resolution. The radicals were generated in a glow discharge of gaseous mixtures in a specially designed discharge cell. The spectra of short-lived radicals published here are of great importance, especially for the detailed knowledge and study of the composition of exoplanetary atmospheres in selected new planets. Today, …
S-Type Stars: Line List For The A²Π-X²Σ⁺ Band System Of Lao,
2023
Old Dominion University
S-Type Stars: Line List For The A²Π-X²Σ⁺ Band System Of Lao, P. F. Bernath, R. Dodangodage, J. Liévin
Chemistry & Biochemistry Faculty Publications
LaO bands are found in the spectra of cool S-type stars. The bands of the A2Π–X2Σ+ transition with v' ⩽ 3 and v'' ≤ 4 are rotationally analyzed, providing spectroscopic constants for the A2Π state. Line strengths are calculated using an ab initio transition dipole moment function, and radiative lifetimes for the A2Π state have also been computed. A line list for the A2Π–X2Σ+ transition of LaO is provided and can be used to determine LaO stellar abundances.
